Charged particle tomography for anatomical imaging

ABSTRACT

Methods, systems, and devices are disclosed for charged particle tomography imaging. In one aspect, a system includes a charged particle tomography scanner (CPTS) unit to detect individual charged particles of an emitted charged particle beam delivered to a subject by a charged particle delivery (CPD) system, and a processing unit to determine the angular trajectory change (scattering) and energy loss of the charged particle beam based on detected trajectory information and produce an anatomical image. The CPTS unit includes two detectors, one positioned between the subject and the CPD system, and the other detector positioned opposite to the first detector to detect the trajectory information of the individual charged particles of the charged particle beam having passed through the first detector and the subject, and a motion control unit to move the detectors, in which the detectors&#39; size covers an area at least that of the beam&#39;s cross-section.

CROSS REFERENCE TO RELATED CASES

This patent document claims the benefit of priority of U.S. ProvisionalApplication No. 61/946,695, filed on Feb. 28, 2014, and U.S. ProvisionalApplication No. 62/027,203, filed on Jul. 21, 2014. The entire contentof the before-mentioned patent applications is incorporated by referenceas part of the disclosure of this document.

TECHNICAL FIELD

This patent document relates to systems, devices, and processes that usecharged particle tomographic imaging technologies.

BACKGROUND

As a charged particle moves through material, Coulomb charges of nucleiof the material generate multiple Coulomb scattering, perturbing itstrajectory. The total deflection depends on several material properties,but the dominant effects are the atomic number, Z, of nuclei and thedensity of the material. Additionally, the charged particle loses energythrough various interactions with the electrons in the material. Thisenergy loss depends on several material properties, but the dominanteffects are density and electron cloud properties of the material. Thescattering and energy loss of multiple charged particles can be measuredand processed to probe the properties of these objects. These propertiescan be analyzed to permit differentiation of materials.

SUMMARY

Techniques, systems, and devices are disclosed for anatomic imaging byusing charged particles, such as protons and electrons.

In one aspect, a system includes a charged particle delivery system toemit a beam containing the charged particles at a subject, a chargedparticle tomography scanner (CPTS) unit to detect individual chargedparticles of the emitted charged particle beam delivered to the subjectby the charged particle delivery system, and a processing unit in datacommunication with the CPTS unit to determine angular trajectory change(scattering) and energy loss of the charged particle beam based ondetected trajectory information. The CPTS unit including a firstdetector positioned between the subject and the charged particledelivery system to receive and detect trajectory information of theindividual charged particles of the emitted charged particle beam, asecond detector positioned at a side of the subject opposite to that ofthe first detector to receive and detect the trajectory information ofthe individual charged particles of the charged particle beam havingpassed through the first detector and the subject, and a motion controlunit configured to move the first detector and the second detector, inwhich the first and second detectors are of a size to cover an area atleast that of the beam's cross-section. The processing unit can generatean anatomical image based on the determined information.

In another aspect, a system includes a charged particle tomographyscanner (CPTS) unit to detect individual charged particles of an emittedcharged particle beam delivered to a subject by a charged particledelivery system, and a processing unit to determine the angulartrajectory change (scattering) and energy loss of the charged particlebeam based on detected trajectory information. The CPTS unit including afirst detector positioned between the subject and the charged particledelivery system to detect trajectory information of the individualcharged particles of the emitted charged particle beam, a seconddetector positioned at a side of the subject opposite to that of thefirst detector to detect the trajectory information of the individualcharged particles of the charged particle beam having passed through thefirst detector and the subject, and a motion control unit configured tomove the first detector and the second detector, in which the first andsecond detectors are of a size to cover an area at least that of thebeam's cross-section. The processing unit further can generate ananatomical image.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a diagram of an exemplary charged particle tomographysystem.

FIG. 1B shows a diagram of an exemplary charged particle tracking arrayincluding strip-type position sensitive arrays for charged particletracking.

FIGS. 2A and 2B show a block diagram of an exemplary system forperforming a charged particle tomography scan.

FIG. 3 shows a block diagram of an exemplary charged particle tomographysystem for anatomical imaging.

DETAILED DESCRIPTION

Medical imaging includes a variety of techniques focused on revealinginternal structures hidden by surrounding tissue. The most common andutilized techniques include photon radiography, magnetic resonanceimaging (MRI), ultrasound and nuclear medicine. Described here is analternative medical imaging technology.

Techniques, systems, and devices are disclosed for anatomic imaging byusing charged particles, e.g., such as protons and electrons. Anatomicalimaging of the disclosed technology can provide tissue differentiationat comparable resolutions to other existing medical imaging techniqueswhile applying a very low or negligible radiation dose, e.g., which is amajor concern in some of the conventional medical imaging modalities.Furthermore, the disclosed anatomical imaging techniques can provide athree-dimensional image, e.g., permitting identification of internalstructures or abnormalities even in cluttered tissue regions.

In some aspects, the disclosed technology includes charged particletomography scanner devices and systems for anatomical imaging. Anexemplary charged particle tomography system includes a charged particledelivery system (e.g., charged particle source), a set of chargedparticle tomography detectors (e.g., dual head charged particletomography scanner dual head) and processing unit that measures thecharged particle beam energy loss as well as the individual trackorientation changes. This information is used to reconstruct atomographic image of the subject. For example, the exemplary chargedparticle tomography detectors and processing unit (e.g., electronics andcomputer systems) process detected signals as data and form ananatomical image, capable of display. The disclosed charged particlebased imaging systems offer a low cost, easy-to-use alternative for 3Dmedical imaging as compared to traditional medical anatomical imagingmethods such as MRI and CT, for example.

Among imaging and sensing techniques, a charged particle tomographysystem of the disclosed technology can be configured to performtomography of a target object under inspection based on measurements ofthe scattering and energy loss of charged particles traversing thetarget object. Such charged particle tomography systems can be usedjointly with or as an alternative to other conventional medical imagingsystems, such as radiography or magnetic resonance imaging. Conventionalradiographic systems operate by applying x-rays to the target andsensing the attenuation of these x-rays in the target by placing asensor on the opposite side of the target. Standard radiography producesa two dimensional image. In some techniques, the x-rays are applied andsensed from many angles, providing a three-dimensional image of thetarget. Radiography applies a relatively high ionizing radiation dose tothe subject. Conventional magnetic resonance imaging (MRI) systems applya strong magnetic field to the target, use radiofrequency emissions toexcite nuclear spin resonances and measure relaxation times of theseresonances. MRI produces a three-dimensional image, but materialdifferentiation is limited because it cannot measure density. A commonpractice is to perform both CT and MRI and combine the images to permitenhanced detection of lesions, anomalies or structures. Because acharged particle tomography measures nuclear properties (e.g.,scattering from the nucleus) and density properties (e.g., energy lossto the electron cloud), it provides similar differentiation capabilityin a single scan.

Currently, medical anatomical 3D imaging modalities typically includeX-ray computed tomography (CT) (also referred to as CT scans or imaging)and magnetic resonance imaging (MRI). CT is a medical imaging procedurethat uses computer processed X-rays to produce tomography images of thebody. MRI makes use of the property of nuclear magnetic resonance (NMR)to image nuclei of atoms inside the body and does not use ionizingradiation for imaging the human body, like CT. In general, MRI cancreate more detailed images of the human body than are possible withX-rays.

A CT scan produces significant amounts of radiation during a typicalimaging procedure. For example, the effective dose for an abdomen scanis about 8 mSv, in contrast to 2.4 mSv from the annual-amount ofbackground radiation. Also, for example, it is widely recognized thatthe more ionizing radiation, the higher possibility for fatal cancerrate. This is especially important to the population who are sensitiveto the ionizing radiation such as children or pregnant women. Thedisclosed technology applies a very low radiation dose relative to CT(less than 1 μSv), reducing radiation exposure risks and permittingscanning of radiation sensitive patients, such as those undergoingchemotherapy or radiation therapy, as well as children or pregnantwomen.

While MRI does not introduce additional radiation, MRI is also a veryexpensive medical imaging modality. For example, not only an MRI unititself is expensive to acquire and maintain, but also requires shieldingin the imaging lab or center for restricting the magnetic fields used inMRI. Also, MRI requires resources to keep its normal operation, e.g.,including medical physicists, technologists, and cooling systems. Inadditional to the cost, MRI also posts some safety issues for certainpopulations, e.g., such as for people who have metal implants, are inpregnancy, and have claustrophobia. Moreover, contrast agent andabsorbed radio waves used in MRI can also pose additional risks for thehuman subjects.

The disclosed charged particle tomography system offers a revolutionaryway to image human body applying a low dose of charged particles. Thecost of the system setup and operation is substantially lower thanexisting modalities like CT and MRI. Furthermore, imaging center or labshielding is greatly reduced.

In one aspect, a system includes a charged particle tomography scanner(CPTS) unit to detect individual charged particles of an emitted chargedparticle beam delivered to a subject by a charged particle deliverysystem, and a processing unit in data communication with the CPTS unitto determine energy loss of the charged particle beam based on detectedtrajectory information, and generate an anatomical image. The CPTS unitincludes an incoming tracking detector positioned between the subjectand the charged particle delivery system to receive and detect incidenttrajectory information of individual charge particles of the chargedparticle beam (e.g., the momentum, incident point location, and incidentangle of each charged particle of the emitted charged particle beam).The CPTS unit includes an outgoing tracking detector positioned at aside of the subject opposite to that of the incoming tracking detectorto receive and detect the outgoing trajectory information of theindividual charged particles of the charged particle beam having passedthrough the incoming detector and the subject. The CPTS unit includes amotion control unit configured to move the incoming detector andoutgoing detector, in which the incoming and outgoing detectors are of asize to cover an area at least that of the beam's cross-section. Forexample, the trajectory information can include, but is not limited to,the momentum, incident point location, and incident angle of a chargedparticle of the charged particle beam.

Implementations of the system can include one or more of the followingexemplary features. In some implementations, for example, the processingunit can provide a control signal to the charged particle deliverysystem to affect the strength or direction of the emitted chargedparticle beam. For example, the processing unit can increase or decreasethe power of the charged particle beam and/or change the aim or beamwidth of the charged particle beam. In some implementations, forexample, the processing unit can provide a control signal to the CPTSunit to move one or both of the incoming detector and the outgoingdetector in individual directions. In some implementations, for example,the system can further include a plurality of surface landmarkspositioned on the subject to scatter the charged particles of thecharged particle beam. For example, the processing unit can beimplemented to form an image in a particular volume of the subject basedon the detected trajectory information and scatter information of thecharged particles.

In some implementations, for example, the incoming detector and theoutgoing detector of the CPTS unit can include ionization based positionsensitive detector arrays. For example, the ionization based positionsensitive detector arrays can include scintillation fiber, drift cellsand/or resistive plate chambers, time projection chambers (TPCs) and/ortracking detectors. In some implementations, for example, the system canfurther include one or more securement units to attach the subject to asurface in a substantially motionless position.

Charged Particle Tomography and Therapy System

FIG. 1A shows a diagram of an exemplary charged particle tomography andtherapy system 100 for volumetric dose monitoring and control. As shownin the diagram, a patient is positioned horizontally on a table orsurface 101, for example, for a charged particle based tomography andtherapy intervention. In other examples, the patient can be positionedin other postures and orientations, e.g., including vertical. Theexemplary system 100 includes a dual head charged particle tomographyscanner unit 120 having a field of view covering at least the radiationbeam cross-section and a mechanism to be able to move the scannerrelative to the beam movement. The charged particle tomography scannerunit 120 can detect the individual charged particles of an emittedcharged particle radiation beam delivered by a charged particle therapyunit 110 at the patient (e.g., positioned on the surface 101). Ingeneral, the charged particle radiotherapy unit 110 can include anaccelerator, beam guide, and other units to direct the charge particlebeam having a determined magnitude or power. For example, the chargedparticle radiotherapy unit 110 can include particle therapy and protontherapy machines and systems, e.g., such as those described in U.S. Pat.No. 5,811,944 and a review article entitled “Emerging technologies inproton therapy” by Jacobus M. Schippers and Antony J. Lomax published inActa Oncologica, volume 50, No. 6, pages 838-850 in 2011, which areincluded as part of the disclosure of this patent document.

The charged particle radiotherapy unit 110 can be implemented using avarious types of particle therapy and proton therapy machines thatinclude a particle accelerator. Examples of the particle accelerator caninclude a synchrotron or cyclotron accelerator that accelerates a beamof charged particles, such as protons, to a desired energy level for usein radiotherapy, including active pencil beam scanning and passivescattering. The synchrotron accelerator can be implemented as a ringstructure that receives particles from a pre-accelerator, stores thereceived particles, and accelerates the stored particles to a desiredenergy. When the desired energy is reached, the accelerated particlesare applied to a patient for radiotherapy treatment. Any unusedparticles in the ring are decelerated and removed. The cyclotronaccelerator can be implemented as a large magnet, such as asuperconducting magnet, that accelerates the particles to a fixed energylevel associated the particular cyclotron accelerator. The acceleratedparticles from the cyclotron accelerator are slowed down by a degraderto a desired energy level. The degrader can include a variable amount ofmaterial, such as graphite. The degrader can be coupled to a collimationsystem and a magnetic analyzer to select the desired energy level andenergy spread of the beam of charged particles applied to a patient forradiotherapy treatment.

Another example of the particle accelerator include a Fixed FieldAlternating Gradient (FFAG) accelerator, which is a synchrocyclotronwith a stronger focusing achieved by splitting up the magnet intoseparate sector magnets of alternating magnetic field. The cavity andRF-generator in the FFAG accelerator are more complicated than thesynchrocyclotron due to the much stronger electric field requirement.The FFAG accelerator can achieve higher beam intensities thansynchrocyclotrons, and allows for particle extraction at arbitraryenergies by switching off the RF-generator when the desired energy hasbeen obtained.

Dielectric Wall Accelerator is yet another example of the particleaccelerator that includes stacked rings of high gradient insulator (HGI)material with conducting sheets inserted at frequent intervals along thestack. Each conducting sheet is connected to a laser driven high voltageswitching circuit that produces an electric field on the inner side ofthe HGI ring when the switches are closed. Successive closing of theswitches shifts the region of strong electric field along the stack andaccelerates protons traveling in phase with the shifting electric field.

In some implementations, the particle accelerators can be implementedusing laser and light transmission components rather than beam linemagnets. Various methods can be applied to accelerate protons usingstrong laser pulses. For example, using Target Normal Sheet Acceleration(TNSA) method, a high intensity laser can irradiate a front surface of asolid target saturated with hydrogen to create plasma. Electrons in theplasma emerge from a rear surface of the target inducing strong electricfields to accelerate the protons out of the rear surface of the target.Proton energies of at least 20 MeV can be achieved using a laser powerintensity of 6×10¹⁹ W/cm² and a pulse length of 320 fs. A laser power of10²² W/cm² can potentially deliver a 200 MeV beam of proton. To selectprotons with the desired energy, dipole magnets and apertures can beused or a suitable scattering material at the location in the analyzingsystem to separate the charged particles in space depending on theirenergy.

In some implementations, radiation pressure acceleration (RPA) uses thelight pressure of a laser pulse incident on a foil to accelerate thewhole foil as a plasma slab. RPA can provide higher proton energies andless energy spread than TNSA.

The dual head charged particle tomography scanner unit 120 can include acharged particle tomography detector 120 a positioned about the patientto receive the emitted charged particle beam and a charged particletomography detector 120 b positioned about the patient to receive thecharged particle beam having passed through the incoming detector 120 aand the patient. For example, in some implementations, the chargedparticle tomography detector 120 a can be positioned above the patientwho might be positioned horizontally on the surface 101 underneath thecharged particle therapy unit 110, and the charged particle tomographydetector 120 b can be positioned below the patient, e.g., underneath thesurface 101.

In some embodiments, for example, the charged particle tomographyscanner unit 120 includes charged particle tracking arrays. The chargedparticle arrays can include multiple layers of position sensitivedetector channels. For example, the charged particle tracking arrays caninclude one-dimensional strip-type scintillation fiber,silicon-microstrip, and/or drift cell sensors. These exemplary sensorscan record the position of the charged particle as it passes through thearray. Position measurements at each layer can be combined toreconstruct the trajectory of the particle in three dimensions as it waspassing through the array. The sensor arrays can detect the momentum,incident point coordinates and incident angles for the incident and exitcharged particles. FIG. 1B shows a diagram of an exemplary chargedparticle tracking array including strip-type position sensitive arraysfor charged particle tracking.

In some implementations, for example, the system 100 can includesecurement and/or positioning units 105 to secure and/or position thepatient on the table 101. The exemplary red dots 199 are surfacelandmarks used for image registration.

FIG. 2A shows a block diagram of an exemplary system 200 for performinga charged particle tomography and radiation therapy treatment plan. FIG.2A shows an exemplary embodiment of the system 200 that may include theexemplary charged particle tomography and radiation system 100 in datacommunication with a processing unit 220. For example, the processingunit 220 can be in data communication with the charged particletomography scanner unit 120 and the charged particle therapy unit 110.In some implementations, the processing unit 220 can determine thetrajectory information of the individual charged particles through thedetectors 120 a and 120 b using charged particle detection processingtechniques as those described in U.S. Pat. Nos. 8,552,370 and 8,536,527,which are included as part of the disclosure of this patent document.The processing unit 220 can determine energy loss of the chargedparticle beam based on the detected trajectory information. Also, theprocessing unit can map the radiation dose (e.g., produce an energy lossmap) as well as generate an anatomical image.

Charged Particle Detection Techniques

Examples of the charged particle detection processing techniques includea method for sensing a volume (e.g., body of the patient) exposed tocharged particles by measuring energy loss of charged particles thatenter and penetrate the volume or are stopped inside the volume withoutpenetrating through the volume. Based on the measured energy loss, aspatial distribution of the charged particles that enter and penetratethe volume or are stopped inside the volume without penetrating throughthe volume can be determined. Using the spatial distribution of theenergy loss of the charged particles, three-dimensional distribution ofmaterials in the inspection volume can be reconstructed.

An exemplary tomography inspection system can include a first set ofposition sensitive detectors located on a first side of (e.g., above) avolume of interest (e.g., the body of a patient) to measure positionsand directions of incident charged particles entering the volume ofinterest. A second set of position sensitive detectors can be located ona second side of (e.g., below) the volume of interest opposite to thefirst side to measure positions and directions of outgoing chargedparticles exiting the volume of interest, or the absence of chargedparticles that have stopped in the volume of interest. A signalprocessing unit can receive data of measured signals of the incomingcharged particles from the first set of position sensitive detectors andmeasured signals of the outgoing charged particles from the second setof position sensitive detectors. The signal processing unit can analyzebehaviors of the charged particles caused by interactions withphysiological structures, tissues and organs within the volume ofinterest based on the measured incoming and outgoing positions anddirections of charged particles to obtain a tomographic profile or thespatial distribution of the physiological structures, tissues and organswithin the volume of interest. The signal processing unit can measureenergy loss of charged particles that enter the volume and penetratethrough the volume of interest, and charged particles that are stoppedinside the volume of interest without penetrating through the volume.The signal processing unit can determine a spatial distribution of thecharged particles that enter the volume of interest and penetratethrough the volume and charged particles that are stopped inside thevolume of interest without penetrating through the volume. The signalprocessing unit can, based on the measured energy loss, use the spatialdistribution to reconstruct the spatial distribution of materials withinthe inspection volume.

In another aspect, a method for sensing a volume exposed to chargedparticles include using a first set of position sensitive detectorslocated on a first side of (e.g., above) the volume of interest (e.g.,body of a patient) to measure positions and directions of incidentcharged particles that penetrate the first set of position sensitivedetectors to enter the volume. The particle detection method can includeusing a second set of position sensitive detectors located on a secondside of (e.g., below) the volume of interest opposite to the first sideto measure positions and directions of outgoing charged particlesexiting the volume of interest or the lack thereof. The particledetection method can include using measurements made by the second setof position sensitive detectors to determine incident charged particlesthat enter the volume of interest and penetrate through the volume ofinterest in addition to charged particles that do not penetrate throughthe volume of interest to reach the second set of position sensitivedetectors. The particle detection method can include determining energyloss of charged particles that enter the volume of interest andpenetrate through the volume of interest in addition to chargedparticles that are stopped inside the volume of interest withoutpenetrating through the volume of interest. The particle detectionmethod can include determining, based on the measured energy loss, aspatial distribution of the charged particles that enter the volume ofinterest and are stopped inside the volume of interest withoutpenetrating through the volume of interest. The particle detectionmethod can include using the spatial distribution of charged particlesthat enter the volume of interest and are stopped inside the volume ofinterest to reconstruct the spatial distribution of materials in theinspection volume.

In another aspect, a method for sensing a volume of interest (e.g., bodyof a patient) exposed to charged particles can include measuring energyloss of charged particles that enter the volume of interest and arestopped inside the volume of interest without penetrating through thevolume of interest. The method of sensing the volume of interest caninclude, based on the measured energy loss, determining a spatialdistribution of the charged particles that enter the volume and arestopped inside the volume without penetrating through the volume. Themethod of sensing the volume of interest can include using the spatialdistribution to reconstruct the three dimensional spatial distributionof materials in the volume according to their respective densities andatomic numbers. From this spatial distribution, objects can be detectedaccording to their atomic number and density.

In another aspect, a method for sensing a volume of interest exposed tocharged particles can include measuring energy loss of charged particlesthat enter the volume of interest and are stopped inside the volume ofinterest without penetrating through the volume of interest. The methodof sensing the volume of interest can include, based on the measuredenergy loss, determining a spatial distribution of the charged particlesthat enter the volume of interest and are stopped inside the volume ofinterest without penetrating through the volume of interest. The methodof sensing the volume of interest can include using the spatialdistribution to detect presence of one or more low density materialswith low atomic numbers.

In another aspect, a method for sensing a volume of interest (e.g., bodyof a patient) exposed to charged particles can include using a first setof position sensitive detectors located on a first side of (e.g., above)the volume of interest to measure positions and directions of incidentcharged particles that penetrate the first set of position sensitivedetectors to enter the volume of interest. The method for sensing avolume of interest can include using a second set of position sensitivedetectors located on a second side of (e.g., below) the volume oppositeto the first side to measure positions and directions of outgoingcharged particles exiting the volume of interest. Using measurementsmade by the second set of position sensitive detectors, incident chartedparticles that enter the volume of interest and do not penetrate throughthe volume of interest to reach the second set of position sensitivedetectors can be detected. The method of sensing the volume of interestcan include determining energy loss of charged particles that enter thevolume of interest and are stopped inside the volume of interest withoutpenetrating through the volume of interest. The method of sensing thevolume of interest can include determining, based on the measured energyloss, a spatial distribution of the charged particles that enter thevolume of interest and are stopped inside the volume of interest withoutpenetrating through the volume of interest. The method of sensing thevolume of interest can include using the spatial distribution toreconstruct the three dimensional spatial distribution of materials inthe volume of interest according to their density and atomic number.From this spatial distribution, objects can be detected according totheir atomic number and density.

In another aspect, a method for obtaining tomographic images of a volumeunder inspection is provided to include detecting an incoming momentumof each incoming charged particles. The method for obtaining tomographicimages of a volume under inspection includes detecting an outgoingmomentum of each outgoing charged particle. The method of for obtainingtomographic images of a volume under inspection includes calculating anenergy loss based on the detected incoming and outgoing momenta. Themethod for obtaining tomographic images of a volume under inspectionincludes using the calculated energy loss to reconstruct the threedimensional spatial distribution of materials in the volume according totheir density and atomic number. From this spatial distribution, objectscan be detected according to their atomic number and density.

In yet another aspect, the information measured in both penetratedcharged particles and trapped charged particles of a volume of interestcan be used to construct tomographic images of the volume. Based on themeasurements of the penetrated and stopped charged particles, aprocessing unit can combine two or three types of measured data oftrajectory changes of penetrated charged particles (e.g., penetratedmuons), the information on stopped charged particles that are trappedinside the volume of interest (e.g., trapped muons), and the informationon energy loss of penetrated charged particles (e.g., penetrated muons)to construct a tomographic image of the volume of interest. This processuses information of different processes inside the volume of interest toimprove the fidelity and resolution of the final image for the volume ofinterest and to reduce the false detection.

The system 100 can be used to apply any of the methods for chargedparticle detection described in this patent document for curative oradjuvant treatment plans through the emission of charged particleradiation directed at target tissue or cells (e.g., including abnormalcells, such as diseased cells or cancer cells). The system 100 can beused in system 200 to implement a charged particle radiation therapytreatment process under the control of the processing unit 220. Forexample, the processing unit 220 can include a detector readout, digitalsignal processing and center data processing unit, the GUI and postprocessing consoles. The charged particle tomography detector unit 120can be configured to have a mechanical structure such as a C-arm toprovide the incoming and outgoing tracking units 120 a and 120 b of thedetector 120 to move and position the detector unit 120, and a motorcontrol system in communication with the processing unit 220 to allowthe detector following the motion of the beam.

The processing unit 220 can include a processor 221 that can be incommunication with an input/output (I/O) unit 222, an output unit 223,and a memory unit 224. The processing unit 220 can be implemented as oneof various data processing systems, such as a personal computer (PC),laptop, and mobile communication device. To support various functions ofthe processing unit 220, the processor 221 can be included to interfacewith and control operations of other components of the processing unit220, such as the I/O unit 222, the output unit 223, and the memory unit224.

To support various functions of the processing unit 220, the memory unit224 can store other information and data, such as instructions,software, values, images, and other data processed or referenced by theprocessor 221. Various types of Random Access Memory (RAM) devices, ReadOnly Memory (ROM) devices, Flash Memory devices, and other suitablestorage media can be used to implement storage functions of the memoryunit 224. The memory unit 224 can store radiation therapy data andinformation, which can include patient diagnostic data, patient imagedata, dosimetry data, prescription data, charged particle radiationtherapy machine system parameters, and hardware constraints, which canbe used in the implementation of the disclosed charged particleradiation therapy treatment plan. The memory unit 224 can store data andinformation that can be used to implement the disclosed charged particleradiation therapy treatment plan and that can be generated from thecharged particle radiation therapy treatment plan.

To support various functions of the processing unit 220, the I/O unit222 can be connected to an external interface, source of data storage,or display device. Various types of wired or wireless interfacescompatible with typical data communication standards, such as UniversalSerial Bus (USB), IEEE 1394 (FireWire), Bluetooth, IEEE 802.111,Wireless Local Area Network (WLAN), Wireless Personal Area Network(WPAN), Wireless Wide Area Network (WWAN), WiMAX, IEEE 802.16 (WorldwideInteroperability for Microwave Access (WiMAX)), and parallel interfaces,can be used to implement the I/O unit 222. The I/O unit 222 caninterface with an external interface, source of data storage, or displaydevice to retrieve and transfer data and information that can beprocessed by the processor 221, stored in the memory unit 224, orexhibited on the output unit 223.

To support various functions of the processing unit 220, the output unit223 can be used to exhibit data implemented by the processing unit 220.The output unit 223 can include various types of display, speaker, orprinting interfaces to implement the output unit 223. For example, theoutput unit 223 can include cathode ray tube (CRT), light emitting diode(LED), or liquid crystal display (LCD) monitor or screen as a visualdisplay to implement the output unit 223. In other examples, the outputunit 223 can include toner, liquid inkjet, solid ink, dye sublimation,inkless (e.g., such as thermal or UV) printing apparatuses to implementthe output unit 223; the output unit 223 can include various types ofaudio signal transducer apparatuses to implement the output unit 223.The output unit 223 can exhibit data and information, such as patientdiagnostic data, charged particle radiation therapy system information,a partially processed charged particle radiation therapy treatment plan,and a completely processed charged particle radiation therapy treatmentplan. The output unit 223 can store data and information used toimplement the disclosed charged particle radiation therapy treatmentplan and from an implemented charged particle radiation therapytreatment plan.

FIG. 2B shows a block diagram of the processor 221 that can include aCPU 225 or a graphic processing unit (GPU) 226, or both the CPU 225 andthe GPU 226. The CPU 225 and GPU 226 can interface with and controloperations of other components of the processing unit 220, such as theI/O unit 222, the output unit 223, and the memory unit 224.

Implementations of the system 200 to perform a charged particleradiation therapy treatment plan can include the following techniques.For example, a patient can be labeled with multiple surface markers 199that can be distinguished in charged particle tomography implemented bythe system 200. For example, the patient can be imaged with thosesurface landmarks labeled during the pre-therapy planning in order toperform the image registration.

For example, in some implementations, the charged particle tomographycan be performed using muons. A muon is a charged particle with aunitary negative charge and a spin similar to an electron, but with amass more than two hundred times greater than an electron. Muons can begenerated by cosmic rays hitting the atmosphere and such cosmic-raygenerated muons penetrate to the Earth's surface. As a muon movesthrough material, Coulomb scattering off of the charges of sub-atomicparticles perturb its trajectory. The total deflection depends onseveral material properties, but the dominant effects are the atomicnumber, Z, of nuclei and the density of the material. Each muon carriesinformation about the objects that it has penetrated. The scattering ofmultiple muons can be measured and processed to probe the properties ofthese objects. For example, a material with a high atomic number Zand/or a high density can be detected and identified when the materialis located, inside low-Z and medium-Z matter. Additional information onmuon tomography detection systems is described in PCT Patent PublicationWO 2009/002602, entitled “IMAGING AND SENSING BASED ON MUON TOMOGRAPHY”.

Muon Tomography Detection System

In an exemplary muon tomography detection system, a set of two or moreplanes of position-sensitive muon detectors can be arranged above avolume or region of interest to be imaged for providing the position andangles (i.e., directions in the 3-D space) of incoming muon tracks. Themuon detectors can measure the position and angles of incoming muontracks with respect to two different directions, e.g., in two orthogonalcoordinates along x and y axes. Muons pass through the volume or regionof interest to be imaged and are scattered to an extent dependent uponthe material occupying the volume or region of interest through whichthe muons pass. Another set of two or more planes of position-sensitivemuon detectors can record outgoing muon positions and directions. Themuon detectors (e.g., drift tubes) in the detectors can be arranged toallow at least three charged particle positional measurements in a firstdirection and at least three charged particle positional measurements ina second direction which is different from the first direction and maybe orthogonal to the first direction. Side detectors (not shown)positioned at opposing locations near the volume or region of interestmay be used to detect more horizontally or lateral orientated muontracks. The scattering angle of each muon is computed from the incomingand outgoing measurements.

The exemplary muon tomography detection system can include a signalprocessing unit, e.g., a computer, to receive data of measured signalsof the incoming or entering muons and outgoing or exiting muons fromcorrespondingly positioned detectors. This signal processing unit cananalyze the scattering of the muons in the volume or region of interestbased on the measured incoming and outgoing positions and directions ofmuons to obtain a tomographic profile or the spatial distribution of thescattering density reflecting the scattering strength or radiationlength within the volume or region of interest. The obtained tomographicprofile or the spatial distribution of the scattering density within thevolume or region of interest can provide reveal the internal makeup(e.g., anatomical structures of the subject) in the volume or region ofinterest. In some implementations, the muon detectors can be locatedabove and below the volume or region of interest. In someimplementations, additional muon detectors can be implemented on thelateral sides of the volume or region of interest to form a box or foursided detector structure that surrounds the volume or region ofinterest.

In processing the measurements associated with the muons in a volume orregion of interest being imaged (e.g., body of a subject), the signalprocessing unit can reconstruct the trajectory of a muon through thevolume or region of interest, measure the momentum of an incoming muonbased on signals from the incoming muon detectors, measure the momentumof an outgoing muon based on signals from the outgoing muon detectors,and determine the spatial distribution of the scattering density of thevolume or region of interest. These and other processing results can beused to construct the tomographic profile and measure various propertiesof the volume or region of interest.

For example, the reconstruction of the trajectory of a muon particlepassing through a detector can include (a) receiving hit signalsrepresenting identifiers of sensors in the detector hit by chargedparticles and corresponding hit times; (b) grouping in-time sensor hitsidentified as being associated with a track of a particular chargedparticle passing through the detector; (c) initially estimating timezero for the particular charged particle; (d) determining drift radiibased on estimates of time zero, drift time conversion data and the timeof the hit; (e) fitting linear tracks to drift radii corresponding to aparticular time-zero; and (f) searching and selecting a time-zero valueassociated with the best of the track fits performed for particularcharged particle and computing error in time-zero and trackingparameters. Such reconstruction of the track based on the time zero fitprovides a reconstructed linear trajectory of the charged particlepassing through the charged particle detector without having to use fastdetectors (such as photomultiplier tubes with scintillator paddles) orsome other fast detector which detects the passage of the muon throughthe apparatus to the nearest few nanoseconds to provide the time-zero.

In another example, the processing for measuring the momentum of anincoming or outgoing muon based on signals from the correspondingincoming or outgoing detectors can include (a) configuring positionsensitive detectors to scatter a charged particle passing though thedetectors; (b) measuring the scattering of a charged particle in theposition sensitive detectors, with the measuring the scatteringincluding obtaining at least three positional measurements of thescattering charged particle; (c) determining at least one trajectory ofthe charged particle from the positional measurements; and (d)determining at least one momentum measurement of the charged particlefrom the at least one trajectory. This technique can be used todetermine the momentum of the charged particle based on the trajectoryof the charged particle which is determined from the scattering of thecharged particle in the position sensitive detectors themselves withoutthe use of additional metal plates in the detector.

In yet another example, the spatial distribution of the scatteringdensity of the volume or region of interest can be determined fromcharged particle tomographic data by: (a) obtaining predeterminedcharged particle tomography data corresponding to scattering angles andestimated momentum of charged particles passing through the volume orregion of interest; (b) providing the probability distribution ofcharged particle scattering for use in an expectation maximization(ML/EM) algorithm, the probability distribution being based on astatistical multiple scattering model; (c) determining substantiallymaximum likelihood estimate of object volume density using theexpectation maximization (ML/EM) algorithm; and (d) outputtingreconstructed object volume scattering density. The reconstructed objectvolume scattering density can be used to identify the internal structureof the volume or region of interest from the reconstructed volumedensity profile. Various applications include cosmic ray-produced muontomography for medical imaging and radiation therapy.

As a muon traverses matter, it encounters Coulomb forces from eachnucleon it passes and is deflected by the Coulomb forces. Each muon canbe measured to provide the scattering angle of the muon trajectory as ameasure of the integrated nuclear density along its path, the thicknessof the material through which the muon has passed based on the distanceof closest approach between linear extrapolations of the trajectory ofthe muon as it enters and leaves the volume or region of interest, andthe location along the muons path where the scattering occurred as thepoint of closest approach between linear extrapolations of the muon'strajectory as it entered and left the volume or region of interest.Three-dimensional representations of the nuclear density in the volumeor region of interest are generated from muon scattering data. Theresolution of this reconstruction is determined by the number of muonspassing through each resolution element (voxel).

Ambiguity in attribution of scattering signal to appropriate voxelneighborhoods produces consistent effects at discrete exposure times,but is not easily characterized over time. One solution is to developindependent background models for discrete exposure times. Exposure timedependent background models can then be subtracted from a reconstructionbeing performed on a volume or region of interest.

For each discrete exposure time, a set of background reconstructions canbe built based on scans of innocuous scenes. This background set shouldinclude as many reconstructions of innocuous scenes as possible, but iseffective with as few as 50-100 scanned scenes. Different ways ofcombining the information from the background dataset can beimplemented. Examples include building the background model by averagingeach voxel's reconstructed value from each reconstruction in thebackground dataset, finding the median reconstructed value, and findingthe 95th percentile value. The background model can be built based onprior knowledge by either using a modeled reconstruction or using ameasured reconstruction of an innocuous scene such as an empty volume orregion of interest.

To properly combine the results of scans of innocuous scenes into abackground model, the position and orientation of the scanned volume orregion of interest must be known relative to the scanner coordinatesystem. The precision of this measurement needs to be of the same orderas the expected resolution of the muon tracking in the volume ofinterest.

Once a background model is developed, the subtraction can be performedin the imaging processing. The value of a voxel in the background modelis subtracted from the reconstructed value for that voxel in aconsidered scene. Thresholds are applied to the background subtractedscattering densities and the probability of the presence of a givenstructure in the volume of interest is calculated from the number of andthe degree to which voxels are found over threshold.

Computationally fast reconstructions of muon tomography data can beperformed by information provided by the closest approach point betweenthe incoming and outgoing trajectories (PoCA), the closest approachdistance between incoming and outgoing trajectories (DoCA) and the anglebetween the incoming and outgoing trajectories. The covariance of theangle and the DoCA can be used to calculate the thickness of thematerial.

The trajectory information of muons can be used to determine thethickness of materials based on muon tomography. Arrays for each voxelalong the incoming and outgoing trajectories symmetrically around thePoCA position according to the calculated thickness are appended with avalue that depends on the scattering angle. After the entire muondataset is considered, the median is taken of the array for each voxeland that value assigned for the reconstruction.

During an exemplary charged particle therapy procedure, if the locationand type of the target tissue (e.g., tumor) require the beam energy tobe high enough so that partial charged particle flux can go through theincoming charged particle detector 120 a and subsequently throughpatient body and reach the surface of the bottom charged particledetector 120 b, then the dual head charged particle tomography scannerunit 120 can provide track information of the charged particles. Thecharged particle tomography scanner unit 120 can detect the chargedparticle beam energy loss and the individual track orientation changesbetween the incoming and outgoing detectors 120 a and 120 b, and providesuch detected signals to the processing unit 220. Notably, the directmeasurement of the charged particle tracks makes it possible for thesystem 200 to use both the detected stop tracks and through tracks ofthe charge particles to generate an energy deposition volumetric image.

In some implementations of the system 100, for example, the surfacelandmarks 199 are used to register the high quality anatomical imageacquired at the therapy planning stage to the scatter image by adoptinga surface landmark based registration algorithm or a volumetric imagebased registration algorithm. For example, this can provide anadditional guidance map (which can be used with scatter imagereconstruction together) for stop image reconstruction.

If the beam energy used for the charged particle radiation therapy istoo low and does not allow sufficient particles to go through thepatient body, for example, then the charged particle therapy unit 110can apply a small fraction of the therapy dose with higher energy (e.g.,enough to allow particles to go through the patient body) for creating ascatter image before performing the therapy procedure.

In some instances such as electron therapy, for example, where theelectron energy only allows them to go through a very finite range, theincoming detector 120 a can be used as the only detector to measure theincident tracks and create the stop image. But additional registrationmethods, e.g., such as optical/ultrasound/X-ray based registrationmethods, can be provided for the same anatomical region to allow theplanning images to be registered for stop image reconstruction.

In some implementations, for example, iterative image reconstruction orhybrid image reconstruction algorithms (combining the scatter image andstop image recon) allows both the energy deposition measurement and thescatter information to be used in the image reconstruction.

FIG. 3 shows a block diagram of an exemplary embodiment of the chargedparticle tomography system for anatomical imaging. The charged particletomography system 3100 shows the charged particle emission unit 110 andthe charged particle tomography scanner unit 120 in communication withthe processing unit 220. The charged particle tomography scanner unit120 can be configured as a multiple head charged particle tomographyscanner with a field of view that can cover individual organs or thewhole body. In some implementations of the cosmic ray charged particletomography anatomical imaging system, the system 3100 includes a motiontracking system 3115. The motion tracking system 3115 can be configuredto correct the blurring caused by body motion of the subject. Forexample, due to relatively long scanning times that may be included inimplementations of the system 3100 for anatomical imaging, as well asbody movements of the subject being imaged, the motion tracking system3115 can be used to mitigate the motion blur for improving the imagecontrast and resolution produced by the processing unit 220. The motiontracking system 3115 can be configured as a video based system orelectromagnetic based system, as well as other type of tracking systems.Also, for example, the system 3100 can include mechanical fixtures suchas masks to reduce the body movement.

In some implementations, for example, the disclosed charged particletomography systems for anatomical imaging, as shown in FIG. 3, canfurther include a detector display readout device 3135 in datacommunication with the data processing unit 220. The display readoutdevice 3135 can include a digital signal processing and/or center dataprocessing unit, a display screen providing a GUI interface with theproduced anatomical image(s) by the system, and post processingconsoles.

Exemplary Implementations

Implementations of the disclosed charged particle tomography systems foranatomical imaging can include one or more of the following exemplaryfeatures. In some implementations, for example, the processing unit 220can provide a control signal to a motion control unit of the chargedparticle tomography system 100 to move one or both of the incomingparticle detector and outgoing particle detector in individualdirections, e.g., which can be used to provide for correction forincoming charged particles. In some implementations, for example, thesystem 100 can further include a plurality of surface landmarkspositioned on the subject to scatter the charged particles. In someimplementations, for example, the system 100 can further include one ormore securement units to attach the subject to a surface in asubstantially motionless position.

In some embodiments, for example, the incoming particle detector and theoutgoing particle detector of the unit 120 can include charged particletracking arrays comprising multiple layers of position sensitivedetector channels. For example, the charged particle tracking arrays caninclude one-dimensional strip-type scintillation fiber,silicon-microstrip, and/or drift cell sensors. These exemplary sensorscan record the position of the charged particle as it passes through thearray. Position measurements at each layer can be combined toreconstruct the trajectory of the particle in three dimensions as it waspassing through the array. The sensor arrays can detect the momentum,incident point coordinates and incident angles for the incident and exitcharged particles. As shown in the diagram of FIG. 1B, an exemplarycharged particle tracking array can include strip-type positionsensitive arrays for incoming and outgoing charged particle detection.

Implementations of the subject matter and the functional operationsdescribed in this patent document and attached appendices can beimplemented in various systems, digital electronic circuitry, or incomputer software, firmware, or hardware, including the structuresdisclosed in this specification and their structural equivalents, or incombinations of one or more of them. Implementations of the subjectmatter described in this specification can be implemented as one or morecomputer program products, i.e., one or more modules of computer programinstructions encoded on a tangible and non-transitory computer readablemedium for execution by, or to control the operation of, data processingapparatus. The computer readable medium can be a machine-readablestorage device, a machine-readable storage substrate, a memory device, acomposition of matter effecting a machine-readable propagated signal, ora combination of one or more of them. The term “data processingapparatus” encompasses all apparatus, devices, and machines forprocessing data, including by way of example a programmable processor, acomputer, or multiple processors or computers. The apparatus caninclude, in addition to hardware, code that creates an executionenvironment for the computer program in question, e.g., code thatconstitutes processor firmware, a protocol stack, a database managementsystem, an operating system, or a combination of one or more of them.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, and it can bedeployed in any form, including as a stand-alone program or as a module,component, subroutine, or other unit suitable for use in a computingenvironment. A computer program does not necessarily correspond to afile in a file system. A program can be stored in a portion of a filethat holds other programs or data (e.g., one or more scripts stored in amarkup language document), in a single file dedicated to the program inquestion, or in multiple coordinated files (e.g., files that store oneor more modules, sub programs, or portions of code). A computer programcan be deployed to be executed on one computer or on multiple computersthat are located at one site or distributed across multiple sites andinterconnected by a communication network.

The processes and logic flows described in this specification can beperformed by one or more programmable processors executing one or morecomputer programs to perform functions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read only memory ora random access memory or both. The essential elements of a computer area processor for performing instructions and one or more memory devicesfor storing instructions and data. Generally, a computer will alsoinclude, or be operatively coupled to receive data from or transfer datato, or both, one or more mass storage devices for storing data, e.g.,magnetic, magneto optical disks, or optical disks. However, a computerneed not have such devices. Computer readable media suitable for storingcomputer program instructions and data include all forms of nonvolatilememory, media and memory devices, including by way of examplesemiconductor memory devices, e.g., EPROM, EEPROM, and flash memorydevices. The processor and the memory can be supplemented by, orincorporated in, special purpose logic circuitry.

While this patent document and attached appendices contain manyspecifics, these should not be construed as limitations on the scope ofany invention or of what may be claimed, but rather as descriptions offeatures that may be specific to particular embodiments of particularinventions. Certain features that are described in this patent documentand attached appendices in the context of separate embodiments can alsobe implemented in combination in a single embodiment. Conversely,various features that are described in the context of a singleembodiment can also be implemented in multiple embodiments separately orin any suitable subcombination. Moreover, although features may bedescribed above as acting in certain combinations and even initiallyclaimed as such, one or more features from a claimed combination can insome cases be excised from the combination, and the claimed combinationmay be directed to a subcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Moreover, the separation of various system components in theembodiments described in this patent document and attached appendicesshould not be understood as requiring such separation in allembodiments.

Only a few implementations and examples are described and otherimplementations, enhancements and variations can be made based on whatis described and illustrated in this patent document and attachedappendices.

What is claimed are techniques and structures as described and shown,including:
 1. A charged particle tomography system for anatomicalimaging, comprising: a charged particle tomography scanner (CPTS) unitto detect at least some of charged particles of an emitted chargedparticle beam delivered to a region of interest of a subject, the CPTSunit including: an incoming charged particle detector positioned at alocation near the region of interest of the subject to detect trajectoryinformation of the at least some of the charged particles of the emittedcharged particle beam detected entering the region of interest of thesubject, an outgoing charged particle detector positioned at a locationnear the region of interest of the subject opposite to the location ofthe entering charged particle detector to detect trajectory informationof the at least some of the charged particles of the charged particlebeam passing through and detected exiting the region of interest of thesubject, and a motion control unit configured to control movement of theincoming charged particle detector and the outgoing charged particledetector; a processing unit in data communication with the CPTS unit,wherein the processing unit is configured to determine angulartrajectory change due to scattering and energy loss of the detectedcharged particles entering and exiting the subject based on the detectedtrajectory information of the detected charged particles entering andexiting the subject, to create a scatter image based on at least aportion of the detected charged particles entering and exiting thesubject, and to produce an anatomical image of the region of interest ofthe subject; a charged particle delivery (CPD) unit to emit the chargedparticle beam including the charged particles at the region of interestof the subject, wherein the processing unit provides a control signal tothe CPD unit to affect a strength and a direction of the emitted chargedparticle beam; and surface landmarks adapted to be positioned over theregion of interest of the subject to scatter a portion of the chargedparticles of the charged particle beam, wherein the processing unit isfurther configured to register the anatomical image with the scatterimage based on the surface landmarks.
 2. The system as in claim 1,wherein the incoming charged particle detector and the outgoing chargedparticle detector are sized to substantially cover an area equivalent toa cross-section of the emitted charged particle beam.
 3. The system asin claim 1, wherein the incoming charged particle detector and theoutgoing charged particle detector are configured as a multiple headcharged particle tomography scanner with a field of view that covers theregion of interest.
 4. The system of claim 1, wherein the motion controlunit is configured to at least partially correct blurring of theproduced anatomical image of the region of interest of the subjectcaused by body motion of the subject.
 5. The system of claim 1, whereinthe motion control unit includes a video camera to provide feedbackinformation on motion of the region of interest of the subject.
 6. Thesystem of claim 1, wherein the motion control unit includes anelectromagnetic based motion tracking system.
 7. The system of claim 1,wherein the motion control unit includes a mechanical fixture to reducebody movement.
 8. The system of claim 1, comprising a display readoutdevice in data communication with the processing unit.
 9. The system ofclaim 8, wherein the display readout device includes at least one of thefollowing: a digital signal processing unit to process data associatedwith the produced anatomical image; a display screen providing a userinterface with the produced anatomical image; or a post processingconsole.
 10. The system as in claim 1, wherein the processing unit isconfigured to provide a control signal to the CPTS unit to controlmovement of one or both of the incoming charged particle detector andthe outgoing charged particle detector.
 11. The system as in claim 1,wherein the detected trajectory information of the detected chargedparticles entering and exiting the subject includes one or more of amomentum, an incident point location, or an incident angle of a givencharged particle of the charged particle beam.
 12. The system as inclaim 1, wherein the incoming charged particle detector and the outgoingcharged particle detector of the CPTS unit include ionization basedposition sensitive detector arrays.
 13. The system as in claim 12,wherein the ionization based position sensitive detector arrays includeat least one of scintillation fiber, drift cells or resistive platechambers, time projection chambers (TPCs) or tracking detectors.
 14. Thesystem as in claim 1, wherein the CPTS unit further includes: anotheroutgoing charged particle detector positioned at a location near theregion of interest of the subject opposite to the location of theincoming charged particle detector and at least partially adjacent tothe outgoing charged particle detector to detect trajectory informationof at least some other of the charged particles of the charged particlebeam passing through and exiting the region of interest of the subject.15. The system as in claim 14, wherein the motion control unit isconfigured to control movement of the another outgoing charged particledetector.
 16. The system as in claim 1, wherein the CPTS unit furtherincludes: another incoming charged particle detector positioned at alocation near the region of interest of the subject to detect trajectoryinformation of at least some other of the charged particles of theemitted charged particle beam entering the region of interest of thesubject; and another outgoing charged particle detector positioned at alocation near the region of interest of the subject opposite to thelocation of the another incoming charged particle detector to detecttrajectory information of the at least some other of the chargedparticles of the charged particle beam passing through the anotherincoming charged particle detector and the region of interest of thesubject.
 17. The system as in claim 16, wherein the motion control unitis configured to control movement of the another incoming chargedparticle detector and the another outgoing charged particle detector.18. The system as in claim 1, wherein the direction of the emittedcharged particle beam is affected by the processing unit configured tochange a beam width of the charged particle beam.
 19. The system as inclaim 1, wherein the strength of the emitted charged particle beam isaffected by the processing unit configured to increase or decrease powerof the charged particle beam.
 20. The system as in claim 1, wherein theprocessing unit is configured to: generate a guidance map based on theanatomical image registered with the scatter image.